JPH023230A - Formation of insulating film - Google Patents

Abstract

PURPOSE:To remove a bubble defect for obtaining a stably flat resin film by making a plate putting force from above at the time of heating resin. CONSTITUTION:After applying resin warnish 42, the force is put from the upper part with a piston 43. When resin itself has a thermosetting property, once a solvent may be made to volatilize followed by hardening. The surface of the piston in contact with warnish 42 is fitted up with a porous substance. It is necessary that the porous substance 44 does not stick to warnish 42 so that fluorine resin or the like is selected. After force is put on a substrate 1 with the piston 43, heating is performed by a heater 45. Warnish 42 generates volume contraction due to the volatilized solvent, a flow is generated by the force of the piston 43 to always maintain flatness of the surface. A resin film having the flat surface can be formed in the stage wherein the volatilization of the solvent is finally finished. The volatilized solvent passes through the porous substance 44 for being discharged to an outside system. Consequently, it is excluded that bubbles are generated between the piston 43 are warnish 42 to produce a defect.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method of forming a film on the surface of a thin film element, and particularly to a method for forming a film on a non-planar part of a substrate having a non-planar part such as an uneven surface on the surface. The present invention relates to a method of forming a coating having a planar surface.

[Conventional technology]

In the process of manufacturing thin film elements such as thin film magnetic heads and multilayer wiring for LSIs, when forming conductor patterns, insulating film patterns, etc., unevenness is inevitably caused by the patterns.

These irregularities become factors such as disconnection of the conductor formed on the irregularities, poor insulation of the insulating film, and dimensional variations in the photoresist pattern in a subsequent process. Therefore, various efforts have been made to eliminate or reduce the unevenness. In particular, flattening using resin is used as an effective means. An example of this is shown in FIG. 2, in which a pattern of a conductor film 2 is formed on a substrate 1. A resin film 3 is formed by coating so as to cover the conductor film 2. here.

Flattening occurs because the resin flows during heat curing after coating. A second conductor film 4 is formed on this resin film 3 to create a two-layer wiring. Since the step difference is alleviated by the resin, step breakage and the like are less likely to occur, allowing for good wiring. However, in the portion 11 where the conductor film 2 is densely wired, the surface 21 of the resin film 3 is flattened, but the conductor film 2
Although the surface 22 of the resin film 3 alleviates the level difference in the conductor film 2 in the portion 12 where the conductor film 2 is roughly wired, it is not completely flattened, resulting in unevenness. Furthermore, although the surface 23 of the resin film 3 formed in the area where there is no conductor film 2 is flat, it has a higher height from the substrate than the surface 21 of the resin film 3 in the area 11 where the conductor film 2 is densely wired. is low. When the second conductor film 4 is formed on the resin film 3, the step difference in the first conductor film 2 is alleviated by the resin, so that problems such as step breakage are less likely to occur. However, on the other hand, the conductor film 4
Since the height of the resin surface on which is formed differs depending on the presence or absence of the conductor film 2, a difference in focal position occurs when forming the photoresist pattern applied on the second conductor film 4, and the height of the resin surface on which the conductor film 4 is formed differs. It becomes difficult to form a pattern well at all positions.

Further, the uneven surface 32 causes pattern defects due to surface reflection during photoresist exposure.

Furthermore, differences in photoresist thickness occur due to unevenness, resulting in deviations in pattern dimensions.

In order to fundamentally solve the above problems, it is necessary to substantially eliminate surface irregularities. Specifically, it is desirable to make the unevenness sufficiently small for the depth of focus of the reduction projection exposure machine of about 1 μm, and a method for this purpose is disclosed in Japanese Patent Laid-Open No. 62-88117.

When heat treating a resin film, there is a method of applying pressure with a flat plate from above to force the resin film to flow. According to this method,
A flat surface can be obtained regardless of the density of the underlying conductor wiring.

[Problem to be solved by the invention]

The above-mentioned conventional technology does not take into consideration the gas generated when heat-treating the resin, and there is a problem in that bubble defects occur locally.

An object of the present invention is to eliminate bubble defects and obtain a stable and flat resin film.

[Means to solve the problem]

The above object is achieved by making the plate to which force is applied from above when heating the resin porous.

[Effect]

The porous plate allows solvent vapor generated from the resin layer, reaction product gas, and moisture vapor to pass through,
Gas does not remain between the plate and the resin, and the generation of air bubbles can be prevented.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. 1st
In the figure, the substrate 1 is placed on a flat stage 41. A pattern of a conductor film 2 is formed on the substrate 1 in advance. Varnish 4 for forming a resin film on the substrate 1
Apply 2. The varnish may be made of various organic resins commonly used for insulation, such as a polyimide resin precursor dissolved in an organic solvent, a phenol resin, or a fluororesin having heat-softening properties. The resin used must either have thermosetting properties itself, or be thermosetting like phenolic resins but have the property of softening once, or be able to be dissolved in a certain type of solvent. It is. After applying the resin varnish 42, force is applied from above with a piston 43. When the resin itself has heat softening properties, the solvent may be evaporated once and the resin may be cured. Piston varnish 42
A porous material 44 is attached to the surface in contact with.

It is necessary that the porous material 44 does not adhere to the varnish 42, and a fluororesin or the like is selected.

If the varnish 42 is made of fluororesin, porous metal or the like is preferably selected. Furthermore, by sandwiching a porous membrane on the surface of the piston 43, it is also possible to make it function as the porous substance 44.

After applying force to the substrate 1 with the piston 43, it is heated by the heater 45. The varnish 42 undergoes volumetric contraction as the solvent evaporates, but the force of the piston 43 causes it to flow, and the surface remains flat at all times. Finally, when the solvent has finished volatilizing, a resin film with a flat surface is formed. The volatilized solvent passes through the porous material 44 and is discharged to the outside of the system. Therefore, air bubbles do not occur between the piston 43 and the varnish 42 and cause defects.

The smaller the pore diameter of the porous material is, the better, as long as it is large enough to allow solvent molecules to pass through, but it is necessary that the varnish does not penetrate into the pores due to the surface tension of the varnish.

When heating a film of a heat-softening material from which the solvent has already been removed to flatten it, adsorbed water will come out during heating.

Gas and the like produced by the reaction or decomposition of the residual solvent 1 are discharged through the porous material 44.

In order to accelerate the discharge of the solvent or suppress reactions such as oxidation, it is also effective to place the entire system in a vacuum container or the like and heat it in a vacuum or in a specific atmosphere. Further, it is also effective to provide uniform heating by incorporating the heating heater 45 inside the stage 41° piston 43.

〔Effect of the invention〕

According to the present invention, gas emitted during resin heating can be promptly discharged from the system, so that a flat film without defects can be formed.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an embodiment of the present invention, and FIG. 2 is a cross-sectional view for explaining the present invention. 1... Substrate, 2, 4... Conductor film, 3... Resin film, 4
1... Stage, 42... Varnish, 43... Piston, 44... Porous material, 45... Heater. 4f Stage 42 Varnish heater

Claims (1)

[Claims] 1. In the step of forming an insulating film on at least a part of the substrate including the non-planar part, the substrate has a non-planar part formed on at least a part of the surface, in which gas is applied to at least a part of the insulating film. A method for forming an insulating film, characterized in that the surface shape of the insulating film is made substantially planar by applying pressure with a solid having a passing portion.